Zoonosis

A zoonosis (plural zoonoses, or zoonotic diseases) is an infectious disease caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from an animal (usually a vertebrate) to a human. Typically, the first infected human transmits the infectious agent to at least one other human, who, in turn, infects others. Major modern diseases such as Ebola virus disease and salmonellosis are zoonoses. HIV was a zoonotic disease transmitted to humans in the early part of the 20th century, though it has now mutated to a separate human-only disease. Most strains of influenza that infect humans are human diseases, although many strains of bird flu and swine flu are zoonoses; these viruses occasionally recombine with human strains of the flu and can cause pandemics such as the 1918 Spanish flu or the 2009 swine flu. Taenia solium infection is one of the neglected tropical diseases with public health and veterinary concern in endemic regions. Zoonoses can be caused by a range of disease pathogens such as emergent viruses, bacteria, fungi and parasites; of 1,415 pathogens known to infect humans, 61% were zoonotic. Most human diseases originated in animals; however, only diseases that routinely involve non-human to human transmission, such as rabies, are considered direct zoonoses.

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